The present invention pertains to pharmaceutical injection devices, and, in particular, to an assembly for removing a shield that protects a needle of a syringe.
Many automatic injector devices include a cap feature which when removed from the device removes a protective shield from a needle of the syringe of the device. The protective shield may consist of a multipart construction including an inner shield and an outer shield which are operatively connected together. The inner shield is relatively flexible or elastomeric and provides a sterile barrier around the needle and forms a seal with, for example, the syringe hub from which the needle extends. The inner shield also may seal the tip of the needle such as in designs where the needle is already in fluid communication with the syringe contents. The outer shield is made of a relatively rigid material and protectively surrounds and engages the inner shield. A pulling of the outer or rigid needle shield from the syringe pulls off the inner shield as well.
The cap feature of the device grips the rigid needle shield and serves to make easier the removal of the shield. The cap feature may be larger in diameter than the protective shield, or provided with a mechanical advantage to aid its removal, so as to be more readily grasped and removed by certain users than if the protective shield was removed alone. When the cap feature is removed from the device, which removal removes the protective shield as well due to the cap gripping the rigid needle shield, the needle is uncovered, although frequently still housed within the device prior to being extended therefrom during use, and ready for an injection.
One known cap feature that grips a rigid needle shield utilizes a two-piece assembly. The first piece includes a plastic cup with a tubular portion designed to fit over a rigid needle shield portion of a protective shield previously mounted to an injection needle. The second piece includes a larger diameter, rigid plastic base cap having a softer, grippable periphery that may be provided via a comolding or two shot molding process. Two openings formed through sides of the tubular portion of the plastic cup define a pair of diametrically opposed grip fingers that are resilient so as to be deflectable. Each finger has an inner surface with serrated ribs, and an outer surface with a ramp formed thereon. After the plastic cup is placed onto the rigid needle shield such that the serrated ribs of the resilient fingers are in angular alignment with detents on the rigid needle shield with which they cooperate, the base cap is mounted to the plastic cup so that the tubular portion of the cup inserts into a cavity of the base cap. During this insertion, the base cap interior surface that defines its cavity engages the ramps of the grip fingers to deflect the fingers inward such that the serrated ribs come into gripping contact with the rigid needle shield. The base cap is so mounted until its radial protruding tabs within the base of the cavity snap fit into an annular recess on the exterior of the cup tubular portion, thereby locking the base cap and the plastic cup together to allow them to function as a unit.
While known cap assemblies for removing rigid needle shields may provide a benefit to users, they are not without their shortcomings. For example, cap assemblies may be complex to make, or not be well suited for gripping only small portions of needle shields that are exposed. Cap assemblies may require forces to install that are unacceptably high, or may, in their mounting during manufacture, bend the needle or shift the protective shield already installed on the needle an unacceptable amount that adversely affects sealing of the needle.
Thus, it would be desirable to provide a puller assembly that can overcome one or more of these and other shortcomings of the prior art.